Solubility and protonation constants of ethylenediaminetetraacetic acid (EDTA) were determined in aqueous NaCl solutions at different ionic strengths (0 <= I <= 6.0 mol.kg(-1)), at T = 298.15 K. Dependence on the ionic strength of protonation constants was modeled by the modified SIT approach on the molal concentration scale. From total solubility, we calculated the solubility of the neutral species So, and from these values, as a function of NaCl concentration, the Setschenow (k(m)) coefficient was obtained, together with the values of K-S0.